The present invention relates to a ball diameter automatic measurement device and method for a rolling bearing. The present invention, more particularly, relates to ball diameter automatic measurement device and method which is capable of determining positions at which a ball are measured based upon the rotation of the ball, and capable of acquiring the average value of measured values and dispersion in the ball diameters at the various positions.
Further, the present invention also relates to ball diameter automatic measurement device and method which is free from the effect of body temperature and a personal error, and which is further hardly influenced by the fluctuation of air temperature.
Japanese Patent Examined Publication No. Hei. 6-54204 teaches a conventional ball diameter measurement device, in which a method of pressing and positioning a ball manually on three planes. The three planes are defined by an upper surface of a fixed board and a pair of surfaces of the notch of a notched groove of a ball holder. After positioning the ball on the three planes, the ball diameter is measured.
In the conventional ball diameter measurement device, as a ball is manually positioned at a measurement point by using a pair of tweezers, it is easily influenced by body temperature and then the temperature drift is large. Since distance between a hand for operating the tweezers and the ball held between the tweezers is so small, the ball is indispensably influenced by the body temperature. Also, as a ball is manually positioned in a measurement position using tweezers, measurement device cannot be covered or accommodated within a closed box having a cover, and then it is readily influenced by the fluctuation of air temperature. Further, as a ball is manually positioned at the measuring position, a personal error is readily made. Therefore, there is a problem that it is difficult to acquire the measurement precision of .+-.0.01 .mu.m or less.